Sawmill carriage setwork



Oct. 10, 1939. T. H. BEST SAWMILL CARRIAGE SETWORK Filed Feb. 11, 193s INV-E-S'LR T H B es 2 om Nm. o Nm. RN

ATTORN EY Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE 3 Claims.

'Ihis invention relates to sawmills, and particularly to the setwork of log carriages.

At present, the rotation of the set shaft, by means of which the head blocks are advanced, is usually controlled by a friction mechanism. The operation of such a mechanism however is hard to control to the nicety necessary for the desired accuracy of advance of the head blocks, and as a result, the thickness of the board sawed from the log with the travel of the carriage, is apt to vary considerably from the intended thickness to which the setworks control is set by the operator. As a result, considerable wastage is incurred in subsequently reducing the over thick boards to the proper dimension, or valuable time is lost in segregating those boards which are too thin from those of the correct dimension.

It is therefore the principal object of my invention to practically eliminate the possibility of an inaccurate advance of the head blocks by the provision of electrically controlled structure by reason of which the rotation of the set shaft is positively halted as soon as the head blocks have reached the position for which the control lever is set.

A further object is to provide a structure for the purpose which can make use of the standard setworks and its control mechanism with but slight alterations or additions being necessary, although it is possible to make such control mechanism much lighter than is now feasible.

A further object of the invention is to produce a simple and inexpensive device and yet one which will be exceedingly effective for the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Figure 1 is a side elevation, partly in section and somewhat diagrammatic, of my improved setworks control structure as applied to the set shaft.

Figure 2 is a diagram of the circuits employed in connection with the structure.

Referring now more particularly to the characters of reference on the drawing, the log carriage is indicated at I, the setworks being mounted on the carriage adjacent one end.

Extending along the carriage above the floor 2 is the set shaft 3, the rotation of this shaft in one direction or the other controlling the advance or retraction of the head blocks in the usual manner.

Upstanding from the floor 2 is the control stand S which comprises a pedestal i in which a vertical shaft 5 is journaled, this shaft being operatively connected to shaft 3 by bevel gearing 6.

Fixed on the shaft 5 adjacent its upper end is the usual ratchet Wheel 'I which cooperates with a xed graduated plate 8 thereabove, said plate being as usual marked in inches or fractions thereof.

The setting lever 9 is turnable on shaft 5 imu mediately under the ratchet wheel, and on its outer end carries an upstanding pawl and handle unit I. This is normally disengaged from the ratchet Wheel, but as usual is adapted to be swung by the operator into locking engagement with the wheel at any point in its circumference, so as to rotate with the wheel in a head-block advancing direction. The above parts are all standard in the setworks ordinarily used in the mills, and I do not change this structure in any way.

The lever 9 however now carries a contact II on its front face, which is adapted to engage a cooperating contact I2 disposed in the path of the lever and mounted on a stop block I3 rigid with the stand S. A wire I4 from the contact I I is electrically connected with a collecting ring I5 on the shaft 5, which ring is also electrically connected with a stationary wire I6. Another wire I'I is connected to contact I2, which is of course insulated from the stand, as is contact I I.

Secured on the set shaft 3 adjacent one end and ahead of the gearing 6, is an exposed friction pulley I8 and a brake drum I9 which is engaged by a magnetic brake device 20, the brake unit being enclosed in a housing 2|. The shaft 3 at said one end is alined with a separate drive shaft 40 22, driven from an electric motor 23 with a reduction gear box 24 therebetween. The adjacent ends of the shafts 3 and 22 are provided with the cooperating parts of a normally disengaged or deenergized magnetic clutch indicated at 25 and enclosed within a housing 26.

The motor is connected to a jack shaft 2 under the oor 2 by a belt drive 28, the jack shaft being parallel to and directly under shaft 3 and having adjacent one end a friction pulley 25 normally clear of but adapted to engage pulley I8. To allow of the necessary vertical movement of the jack shaft for such engagement, I interpose a flexible coupling in the jack shaft just ahead of the pulley and beyond the fixed shaft bearings 55 3|. The pulley 29 is lifted by the operator into engagement with the pulley I8 by means of a rocking lever unit 32 mounted under the floor 2 and extending lengthwise of shaft 21. At one end, the lever engages a yoke and collar unit 33 on shaft 21 adjacent the pulley 29, and at the opposite end is provided with an upstanding depressible stem 34 carrying a pedal 35 on its upper end positioned convenient to the operator stationed adjacent the control stand. A spring 36 preferably applied to unit 33 acts to positively hold the pulley 29 clear of pulley I3 when pressure on the pedal is removed.

The magnetic brake and clutch are designed to operate on direct current, whereas alternating current is frequently all that is available from the power lines leading to the mill. In this case, a D. C. generator 31, of sufficient capacity to supply the necessary current for the purpose, is driven from the motor 23, which is constantly operating.

The wires 38 of the magnetic clutch are connected to the supply wires 39 from the generator and a normally open magnetic switch 43 is interposed in the wires 38.

The wires 4I from the magnetic coil 42 of the brake unit are also connected to the wires 3Q and a normally open magnetic switch 43 is interposed in wires 4I, one of the wires 44 from the magnet 45a, of switch 40 is connected to one of the wires 39, while the other wire 44 is connected to one xed contact 45 of a special switch, the other fixed contact 43 of which is connected to the other wire 39. This special switch is mounted convenient to the operator at the control stand. The contacts 45 and 46 are horizontally spaced from each other, and are adapted to be bridged, to close the circuit, by a rocking contact blade 41 pivoted intermediate its ends in the switch box. A push button member 48 projects upwardly from the end of the blade which is uppermost when the switch is open, while a Similar member 69 projects upwardly from the opposite end of the blade. Associated with the member 49 below the blade is the core 50 of a solenoid coil 5I, one end of which is connected to wire I1. The other end of the solenoid coil is connected to one of the wires 52 of magnet 43a of switch 43, the other wire 52 being connected to one supply wire 39. The wire I6 is connected to the other supply wire 39, so that a circuit through the solenoid coil and magnet 43a is closed when the contacts Il and I2 are engaged.

In operation, when it is desired to advance the head blocks, the setting lever s is engaged with the ratchet wheel at the desired point as deter- 'mined by a reading against the Xed gauge plate G. The button 48 is then depressed to cause the blade 41 to engage contacts 45 and 4G. A circuit is thus obviously closed through the magnet 45a, causing switch 40 to be closed. A circuit is then closed through the magnetic clutch, causing shaft 3 to be driven from shaft 22. The shaft 5 and ratchet wheel are also rotated, causing the lever 9, which has been locked to the ratchet wheel, to be turned toward the stop block. The head blocks are now being advanced by the rotation of shaft 3.

As soon however as the contacts EI and I2 engage each other with the rotation of the lever, a circuit is at once closed through the solenoid coil I and magnet 43a. lIhe solenoid being thus energized, the core 53 is instantly pulled down, moving switch blade 41 to an open position and breaking the circuit to magnet 46a. The switch 4U immediately opens, breaking the circuit to the magnetic clutch and causing the clutch to be immediately disengaged. At the same time, the magnet 43a of switch 43 being now energized, the switch 43 is closed. This closes the circuit to the brake, which is at once applied.

Since electrical apparatus acts almost instanta neously, the clutch releasing and braking action take place at the same time, preventing any possible coasting of the set shaft, and insuring its halting at the point position necessary to give an accurate positioning of the head blocks corresponding to the initial setting of the lever 9.

It is of course to be understood that the magnetic brake is of a size and power such that it will stop the set shaft the instant the brake is applied.

The solenoid remains energized as long as the contacts II and l2 are engaged, providing a safety feature against possible inadvertent or accidental depression of the starting button 48. When the lever 9 is pulled away from the contact I 2 by hand, the circuits to the solenoid and brake are at once broken, but the switch blade 41 remains in an open position, and can only be closed by another hand movement.

If it is desired to advance the head blocks Without any accurate positioning thereof, the lever remains disengaged from the ratchet wheel, and the starting and stopping of the set shaft is controlled by hand depression of the buttons 48 and 4&3 respectively.

When it is desired to retract the head blocks, after the contacts Il and l2 are separated, it is only necessary to depress pedal 35, bringing pulleys 29 and I8 into engagement.

Since the jack shaft 21 is constantly driven from the motor in the same direction as the drive shaft 22, the set shaft will now be rotated in the opposite or retractive direction, such rotation continuing as long as the foot pressure is retained on the pedal.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as dened by the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. A setworks control mechanism comprising with a set shaft, a rotatable setting lever and means to connect the lever to the set shaft for rotation therewith through any selected arc; a constantly turning drive shaft, a normally disengaged magnetic clutch between the drive shaft and set shaft, a normally open circuit for the clutch, a normally released magnetic brake associated with the set shaft, a circuit for said brake including a normally open switch, a hand switch to close the clutch circuit whereby to engage the clutch and rotate the set shaft and lever, another normally open circuit, means to close the brake circuit by the closing of said other circuit, switch contacts in said circuit closed by the arrival of the lever at the end of said selected arc, and means actuated by the closing of said other circuit to open said hand switch and including means to prevent reclosing of said hand switch until said other circuit is again open.

CTI

2. A structure as in claim 1, in which the hand switch includes a blade movable in one direction to close the switch and in the opposite direction to open the switch and said last named means comprises a solenoid coil interposed in said other circuit, and a core for the solenoid connected to the blade and disposed to cause the blade to be pulled in said opposite direction when the solenoid is energized.

3. A setworks control mechanism comprising with a set shaft, a rotatable setting lever and means to connect the lever to the set shaft for rotation therewith through any selected arc; a constantly turning drive shaft, a normally disengaged magnetic clutch between the drive shaft and set shaft, a normally open circuit for the clutch, a normally released magnetic brake associated with the set shaft, a circuit for said brake including a normally open switch, a magnet to close said switch, a normally open circuit for the magnet, a hand switch to close the clutch circuit whereby to engage the clutch and rotate the set shaft and lever, a switch in said magnet circuit comprising a contact on the lever and a Xed contact positioned in the path of movement of said lever contact to be engaged thereby with the rotation of the lever to the end of said selected arc whereby the magnet circuit will be closed and the brake circuit switch closed, and means actuated by the closing of said magnet circuit to also open the hand switch.

THEODORE H. BEST. 

